1. Field of the Invention
The present invention relates to a liquid ejection apparatus and an image forming apparatus, and more particularly, to a liquid ejection apparatus in which suctioning or pressurization of liquid inside a plurality of nozzles provided in a liquid ejection head is carried out in a state where a cap is in contact with a nozzle surface of the liquid ejection head.
2. Description of the Related Art
An inkjet recording apparatus forms a desired image on a recording medium by ejecting ink droplets selectively from a plurality of nozzles installed in an inkjet head (hereinafter, simply called a “head”). In recent years, very large numbers of nozzles have been installed at high density in the head, in order to achieve high-quality recording and high-speed recording.
The nozzles of a head of this kind are always in an ink-filled state, and if a state where no ejection from a nozzle is performed continues for a long period of time, then the ink in the vicinity of the meniscus (i.e., ink surface) increases in viscosity, the ink dries, and ejection defects such as nozzle blockages may occur eventually. Therefore, it is necessary to carry out a maintenance operation which expels the defective ink inside nozzles, by placing a cap on the nozzle surface of the head and then suctioning or pressurizing the ink inside the nozzles. However, in many cases, these maintenance operations are implemented at all of the nozzles, and therefore a large amount of ink is consumed wastefully.
Japanese Patent Application Publication No. 2000-225715 discloses an inkjet printer which suppresses wasteful consumption of ink by dividing the nozzles into a plurality of nozzle groups and suctioning the nozzles individually on a nozzle group basis.
However, in the inkjet printer disclosed in Japanese Patent Application Publication No. 2000-225715, it is necessary to provide a suction selection device, such as an electromagnetic valve, on the cap side, for each nozzle group unit. Hence, the costs tend to be high.